Spray nozzle



y 966 D. B. BAKER 3,249,305

SPRAY NOZZLE Filed Nov. 18, 1963 United States Patent C) 3,249,305 SPRAY NOZZLE Donald B. Baker, Foxhoro, Mass., assignor to Bird Machine Company, Walpole, Mass., a corporation of Massachusetts Filed Nov. 18, 1963, Ser. No. 324,472 16 Claims. (Cl. 239-113) This invention relates to spray or discharge nozzles and is particularly pertinent to shower pipes or other pipes having a plurality of nozzles to be operated in unison.

In the main, this invention concerns improvements in the construction and operation of nozzles of the type disclosed in my US. Patent No. 3,073,529.

One of the objects of the present invention is to provide an improved nozzle of the type shown in my patent having a movable valve member that can be seated under the influence of fluid pressure over a wide range of pressures and that can be moved from one position to another by snap action over this range of pressures.

Another object of this invention is to provide a spray nozzle of the above type which provides a unique strainer that prevents foreign material from accumulating at the main outlet, or from being discharged upon the surface being sprayed, even when the nozzle is actuated for selfcleaning.

Still another object of my present invention is to provide a nozzle of the above type which has the advantages of my patent in requiring no finely machined parts and having a movable valve member that is relatively free from mechanical restraint, responsive only to changes in fluid conditions, but which is surer in action and relatively free of vibrational influences.

Still another object of my invention is, in general, to provide a nozzle having improved self-cleaning properties.

.One aspect of the invention lies in the particular form of the movable valve member. This member has a rounded portion for seating in a circular cross-section passage to close an outlet, but is elongated and provides oppositely directed piston surfaces exposed to separate ports which control the position of the valve member. Communication between the ports need not be completely sealed, and for this reason fine clearances are avoided so the entire valve assembly can be mass produced on a screw machine.

' Another aspect of the present invention is the use of this elongated valve member to form one side of a restricted flow path, preceding a main outlet that is continually open, the restricted flow path straining out foreign matter that would otherwise lodge downstream in the nozzle. This flow path can be widened by movement of the valve member to purging position while counterflow from the upper port can purge the foreign material out of the nozzle, through the lower port, and not out the nozzle outlet.

Still another aspect of the invention lies in the use of a hollow valve member to define both auxiliary and main outlets, while still enabling the operation of a pair of ports to move the valve member independent of any mechanical aids such as springs or the like.

These and other objects and aspects will be apparent from the drawings and from the description which follows.

In the drawings:

FIG. 1 is a vertical, longitudinal cross-sectional view of a shower pipe with nozzles according to the present invention;

FIG. 2 is a vertical cross-sectional view on a magnified I ice FIG. 5 is a view similar to FIG. 2 of another preferred embodiment of the invention;

FIG. 6 is a horizontal cross-sectional view of the embodiment of FIG. 5 taken on line 66 thereof;

FIG. 7 is a vertical cross-sectional view of another nozzle employing an elongated valve member;

FIG. 8 is a view, similar to FIG. 7, with portions broken away, showing the movable member in closed position;

. and

FIG. 9 is a horizontal cross-section of the embodiment of FIG. 7 taken on line 99 thereof.

As shown in FIGS. 1 and 2 of the drawings, one embodiment of the present invention comprises an elongated, generally cylindrical pipe member 10 divided by means of a longitudinally extending web 12 into a pair of manifolds 14 and 16. An inlet pipe 18, together with a valve 20, provide means for introducing a supply of fluid into manifold 16 with the valve in the location shown in solid lines, with valve disc 21 sealing the inlet passage from drain chamber 22 and valve disc 23 sealing the inlet chamber 18 from manifold 14. The valve has an alternative position, in which it is shifted vertically carrying valve discs 21 and 23 to the dotted lines shown, connecting manifold 14 to the inlet 18 while connecting manifold 16 to a drain pipe, e.g. to atmospheric pressure, at substantially reduced pressure from that at the inlet chamber 18.

Mounted along the length of pipe 10 are a plurality of spray nozzles 30, 30. The spray nozzle comprises a body member 32 along with removable spray deflector 42 held in place by a threaded cap on the body member. The assembly provides an elongated, generally cylindrical valve chamber 36 which has a port 38 at one end communicating with manifold 16, serving as a main inlet and a main outlet 40 defined at the spray deflector member 42. An auxiliary outlet 44 is provided, outlet 44 preferably being of considerably greater capacity than main outlet 40. In the preferred embodiment, auxiliary outlet 44 is circular in cross-section and is provided with a circular cross-section valve seat 46,-converging-in the outward direction. An annular seat 50 is also provided at the inner end of main inlet 38. Confined within valve chamber 36 and free to move from one end to the other is an elongated valve member 52 having a rounded upper end 53, preferably of spherical shape, adapted 'to tightly seal against seat surface 46 to close auxiliary outlet 44.

The valve member. has an elongated mid-section 55 extending from the rounded end 53 toward port 38, and at the opposite end an enlarged portion 57 substantially filling the cross-section of the elongated valve chamber 36 but with no fine clearance relation thereto. The end surface 59 of the enlarged portion 57 isdirected toward port 38 for the purpose of acting as a piston surface. The oppositely directed surface 61 outside of the and portion 55 acts as a piston surface, and there is provided a port 54 in the wall of valve chamber 36, which communicates with manifold 14 and which serves as an auxiliary inlet in this embodiment of the invention. This port 54 is above piston surface 61 when the valve member is in closed or upper position, so that this piston surface 61 is always exposed to the influence of port 54. At the largest cross-section of the enlarged member 57, only a narrow passage is defined adjacent the walls of the valve member so that communication between ports 54 and 38 is limited. Accordingly, in normal operation, with the valves as shown in FIG. 1 in solid lines, fluid enters through port 38, passes between enlarged portion 57 and the chamber walls, and thence to the volume defined above the piston surface 61. The valve member is provided with a bore communicating with this volume and defining, at its uper end, the main outlet, in conjunction with the spray deflector 42, the surface of the valve member defining one side of the discharge orifice.

In accordance with my prior patent, the manifold 14 is charged with liquid at the same pressure as the manifold '16, e.g. by leakage between the enlarged member 57 and the chamber walls thence through port 54. Then, when it is desired to open the auxiliary outlet, the manifiold 16 connected to the port 38 is discharged to waste while the manifiold 14 is connected with the inlet 18. The sudden change in pressures allows the relatively limited piston area of 61 to receive a greater total force than that applied upon enlarged piston surface 59 and acts, in conjunction with the change in flow of. liquid in the chamber, to drive the valve member down and upon the auxiliary outlet 44 whereby the nozzle is cleaned.

Tests have demonstrated that such elongated valve members, with piston surfaces as described, have a very positive action over a wide range of operating conditions, .while still enabling relaxed machine tolerances, the clearance between the valve members and the walls being an advantage rather than a disadvantage.

But, furthermore, according to the invention the clearance between the valve member and the chamber walls serves an additionalfunction. In the closed position, as shown .in FIG. 2, the enlarged lower end 57 of the valve member defines a restricted flow path R with the wall 63 of the valve chamber, and this flow path has a width less than the width-A of the bore through the valve member, and less than the width B of the orifice. Accordingly, the restricted passage serves as a strainer. This is an important advantage because in the paper industry water carries fibers and other foreign material, which the restricted flow path can strain out. Any particle that could be retained in the nozzle and allowed to agglomerate with other particles, will do so at the restricted flow path R rather than downstream therefrom. When it is decided to clean the nozzle, port 38 is open to drain or port 54 is open to inlet pressure, as already described, and a counterflow of liquid occurs through the restricted path R, while the piston member reactsto the change in fluid conditions to move toward port 38, this counterflow rapidly carrying the foreign material out the port 38 before the valve member reaches seating position on valve seat 50.

In this embodiment the bore C in which the enlarged end of the valve member is confined is gretaer than the bore D at the point where the restricted passage is defined when the valve member is in the up position, so that the downward movement of the valve member enlarges the flow path, further aiding in the loosening of and carrying out of the foreign material.

Referring to FIG. 3, it will be seen that therestricted flow path R is of annular form, and preferably it has a much larger total flow cross-section than the bore through the valve member or the orifice, whereby little fluid pressure drop is involved in the fluid passing through the restricted passage. To insure that the passage is not larger on one side than on the other, a locating device is employed, now to be described.

Referring still to FIG. 2, a locating ring 65, of larger cross-sectional dimension than the rounded end portion 53 of the valve member is provided to engage the wall 67 of a passage leading to the auxiliary outlet 44, the ring 65 engaging this passage in the seated position, thus, in

' cooperation with the seating of end portion 53 upon seat 46, axially locating the valve member so as to insure constant cross-section to the flow path R throughout its circular extent. The passage 67 has a limited inward extent, whereby the ring 65 can move inwardly beyond the wall of passage 67 to the larger chamber 36, when the nozzle is to'be purged, so that fluid can proceed from auxiliary port 54 around ring 65, thence along the upper end of the valve member to the auxiliary outlet 44. The end portion 53 of the valve member can serve as a pilot, remaining within the passage 67 when the valve member has been withdrawn to its retracted position, thus serving to lead the valve member and in the closed position.

the ring 65 into the passage 67 on return movement when normal operation of the nozzle is to be achieved. A particular advantage of this construction is that all of the surfaces of the valve member, including the ring 65, are surfaces of revolution, easily adapted for mass production on screw machines.

Referring to FIG. 5, another embodiment of the invention is shown, which differs from that of FIG. 2 in the particular construction of the straining surfaces. In the embodiment of FIG. 5 a cylindrical chamber 70 houses the enlarged end of the valve member 52' in all positions. Referring to FIG. 6, the enlarged portion 57"of the valve member is provided with three spaced-apart locator =projectors 72 located to engage the inner wall of cylinder 70 and the define therebetween'the restricted flow path R forstraining out the foreign material. Because of the locating effects of the members 72 on the enlarged portion, the upper guide shown in FIG. 2 can be dispensed with, though they can also be employed where very accurate positioningof the valve member is desired.

Despite the cylindrical form of the chamber 70, so that the relative cross-sections of the large portion 57' of the valve member and the chamber do not change during movement of the valve member, still it has been found that the foreign material will be moved by the counterflow before the enlarged portion 57' is able to seat on the lower restraining surface at the first port'38'. This occurs apparently because of the inertia of the valve member,

which allows the counterflow fluid to sweep ahead of it during retraction, to carry the foreign matter out, this purging action being aided also by the relative movement of the valve member with respect to the chamber. Another difference in the embodiment of FIG. 5 over that of FIG. 2 is the particular-shape of the enlarged portion 57, here spherical. It should be understood that although no particularshape is critical, it is desired that the flow cross-section leading toward and away from the restricted flow path R should be changed gradually, rather than abruptly, for the sake of good hydraulic'fiow. The spherical shape of FIG. 5, or the lower left ellipsoidal shape of the enlarged portion of FIG. 2 define such flow paths, but other progressive shapes are also useful.

Other, though generally more complicated, forms of the self-straining nozzle can be provided. In one such embodiment, not shown, the valve member could be provided with a longitudinal bore completely therethrough, andan auxiliary piston member could be employed in the normal condition to seat in the inward end of the valve member. The valve member could be sealed to the outer chamber walls and the auxiliary member could define with the main valve member a restricted flow path whereby the fluid could proceed through the flow path, through the elongated bore in the valve member and thence to the main outlet defined at the end of the I valve member.

On retraction, the second or auxiliary port could direct a back flow of liquid through the outer end of the valve member,- thence along its entire length, to unseat the auxiliary piston and to purge the restricted flow path. 1

In another conceivable arrangement, notshown, the valve member could employ an O ring to positively seal against communication between the first and second-ports The inner end of the valve memb'er could define with the chamber walls a restricted flow. path, and between this flow path and the O ring seals, a passage could be formed, opening into a bore in the valve member that extends to the main outlet. Here again the flow from the main inlet would be sealed from the auxiliary inlet in the normal condition. or downward movement of the valve member could open the restricted path, and the O ring assembly then could be made to unseal with such movement to allow fluid to.

proceed from the auxiliary inlet around the O ring, thence between the surfaces that normally define the restricted flow path.

-In common with all of these embodiments is the fact Retraction that the port toward which the valve member moves for purging is used as the normal supply, that end of the valve member cooperates with an additional surface to provide a restricted flow path for straining out foreign material, the main supply proceeding through the flow path to the main outlet, and the auxiliary inlet is positioned to cause a counterflow through the restricted flow path when purging is to be accomplished. Also, it is preferable that the surfaces defining the flow path are relatively movable upon the change in fluid flow conditions for purging, and perferably these surfaces move apart then to allow greater freedom for the foreign material to be swept out by the counterflow thence through the main inlet.

The foregoing embodiments offer a great improvement in operation particularly because of the purging of the foreign matter out-of the nozzle assembly without its being projected through the main or auxiliary outlet. It will be appreciated that shower pipes are employed to clean delicate surfaces such as Fourdrinier wires, and any discharge of foreign material onto the delicate surface is antagonistic to the main aim of using the shower in the first place. Also, it will be appreciated that, without an internal strainer, foreign material tends to agglomerate in the nozzle, and in self-cleaning nozzles heretofore employed, at least a good portion of this agglomerated material was discharged through the main or auxiliary outlet during flushing, and thus was projected against the Fourdrinier wire or other delicate surface, to cause difficulties. Now, with the straining means of the present invention, all material that is big enough to be retained is strained out at the restricted passage, and on actuating the valve to bring to cleaning position, a counterflow occurs through the nozzle flowing the foreign material eg, the tolerances which screw machines can produce,

which are very sloppy compared to the tolerances required in air or hydraulic cylinders of the prior art. It will be observed that leakage between the movable piston and the housing is employed to advantage, rather than being a deterrent. Furthermore, at least in the preferred embodiment, all ofthe parts of the nozzle are of rigid material that cannot be deformed, cannot badly corrode, and there is no such thing as a spring employed, upon whose critical forces the valve must depend.

Referring to the embodiment of FIGS. 79, again an elongated valve member 52" is shown having a rounded upper end 53" adapted to seat to seal the auxiliary outlet, and the valve member having a bore that defines with the deflector member 42 the main outlet orifice.

Also, as with the foregoing embodiments, the inner end 57" of the valve member is enlarged and defines oppositely directed piston surfaces exposed to the effect of the two ports 38" and 54". Also, an elongated cylindrical tube '70 confines the elongated valve member to substantially vertical movement, though without substantial mechanical restraint so that the valve member can be operated by change of the fluid condition at the two ports. As is shown in FIG. 9, as well as in the other figures, the seat 46" defining the auxiliary outlet is of circular cross-section, but it is asymmetrically located with respect to the axis 100 of the chamber 70", whereby, as seen in FIG. 8, the enlarged inner end 57" of the valve member is caused, because of the asymmetrical arrangement, to engage one of the walls 57a of the chamber, this wall being on the same side as the spray outlet, while a loose fit exists between the valve member and chamber so that a space 102 exists on the opposite side. Thus, though there is no critical machining, the main outlet 40" is always held in the operating position. This is achieved through the limiting effect of wall 57a that restrains the valve member from pivoting at the auxiliary outlet seat. It should be understood that since the valve 6 member defines one side of the orifice, if the valve member were allowed to pivot in the counterclockwise direction, as seen in FIG. 8, it would pinch off the main outlet 40".

Another aspect of this embodiment is the fact that a flat surface 104 is provided on the rounded inner end of the valve member which seats on auxiliary seat 50". This is a very simple means of solving the water hammer problem that otherwise results due to rapid oscillations of the pressure in the two chambers which cause similar oscillation of the valve member. The slight leakage that occurs past the flat 104 at the seat dampens the pressure differential and prevents water hammer. I

As will be evident from the foregoing description, certain aspects of this invention are not limited to the particular details set forth as examples, and it is contemplated that various and other modifications and applications of the invention will occur to those skilled in the art. It is therefore intended that the appended claims shall cover such modifications and applications as do not depart from the true spirit and scope of the invention.

What I claim is:

1. In a spray nozzle of the type having a main outlet, an auxiliary outlet adjacent said main outlet, a pair of ports, a valve member movable to closed position at said auxiliary outlet and also movable away from said auxiliary outlet toward one of said ports in accordance with the rate and direction of flow through said ports and outlets, said main outlet remaining open in all positions of said valve member, the improvement wherein said valve member is elongated, said valve member having a rounded end portion adapted to seat upon a sur face defining a circular cross-sectioned converging passageway, for closing said auxiliary outlet, said elongated valve member in the closed position extending from said rounded end portion past said second port in the direction of said first port, said valve member defining oppositely directed piston surfaces, the first piston surface directed toward said first port, opposite from said outlet, and exposed to the pressure influence of said first port at all positions, and the second, oppositely directed piston surface exposed to the pressure influence of said second port at all positions, means including said movable valve member limiting communication between said ports, said valve member being substantially free of mechanical restraint, responsive to increase and decrease of fluid pressures at said first por-t relative to that at said second port to move between open and closed positions, said second por-t being in free communication with said auxiliary outlet when open.

2. The spray nozzle of claim 1 wherein said means preventing f-ree communication between said ports includes a chamber through which a portion of said valve member slides, said portion located between said two ports in closed position, and means locating said portion of said valve member relative to said chamber, when in closed position, to define a restricted flow path from said first port, a passage communicating with said restricted flow path, supplying said main outlet with fluid, said flow path having a width less than that of said passages and said main outlet whereby when said auxiliary outlet is closed said main outlet can be supplied from said first port, through said restricted flow path, with foreign matter strained out at said restricted flow path, and reduction of pressure at said first port can produce a counterflow from said second port through said restricted flow path to said first port to remove said foreign matter.

3. The spray nozzle of claim 2 wherein said portion of said valve member and said chamber, defining said restricted flow path, are cooperatively shaped to move apart upon movement of said valve member toward said first port, to at least partially enlarge said restricted flow path to aid in the removal of said foreign material.

4. The spray nozzle of claim 2 wherein an open bore passes from communication with said restricted flow path, through said valve member to a central opening in said rounded end surface at said auxiliary outlet, said opening defining said main outlet, said valve member, inwardly'from said rounded end, defining a locating ring of larger diameter than said end, an upper portion of said nozzle defining a positioning surface engaging said ring in the closed position, positioning said valve member centrally, said restricted flow path defined on opposite sides by said valve member through the cooperation of said central positioning of said valve member, said valve member in the open position located to allow flow from said second port, past said locating ring to said auxiliary outlet.

5. The spray nozzle of claim 2 wherein said valve member has a mid-portion having a first reduced crosssectional area transverse to the direction of its movement, and the end portion of said valve member exposed to said first port being joined to said mid-portion and being enlarged to a substantially greater cross-sectional area, the free end surface of said enlarged portion defining said first piston surface, the free surface of said enlarged portion directed oppositely from said first piston surface defining, at least in part, said second piston surface, said enlarged portion at its largest point having a circular cross-section, a circular cross-section tube defining said chamber extending from said first port to said second port, and at least three protrusions from one of said chamber and enlarged portion locating said valve member centrally in said tube and defining said restricted flow path therebetween.

r 6. The spray nozzle of claim 1 wherein an open bore passes from communication with said second port, through said valve member to a central opening in said rounded end surface'at said auxiliary outlet, said opening defining said main outlet.

7. The spray nozzle of claim 1 wherein said rounded 8. In a spray nozzle of the type having a main outlet,= an auxiliary outlet adjacent said main outlet, a pair of ports, a valve member movable to closed position at said auxiliary outlet and also movable away from said auxiliary outlet toward one of said ports in accordance With the rate and direction of flow through said ports and outlets, said main outlet remaining open in all positions of said valve member, the improvement wherein said valve member is elongated, said elongated valve member in the closed position extending from said auxiliary outlet past said second port to an inner end disposed toward said first port, said first port providing the normal supply for said main outlet, said valve member allowing the passage of fluid from said port to said main outlet, said valve member in the closed position defining, with a relatively movable, cooperating surface,-

a restriction in the normal supply path for said main outlet, said restriction having a width less than that of said main outlet but a total cross-sectional area substantially greater than that of said main outlet, said restriction shaped to prevent foreign matter reaching said main outlet, said valve member and cooperating surface constructed and arranged to move relatively upon the reduction of pressure at said first port and to receive a counterfiow from said second port whereby said foreign matter can be flushed from said cooperative surfaces that normally define said restriction.

' 9. The spray nozzle of claim 8 wherein an open bore extends from communication with said restriction through said valve memberto an opening in the end thereof, said opening defining said main outlet.

10. 'In a nozzle of the type having at least one outlet,

a pair of ports, a valve member movable to closed position at said outlet and also movable away from said outlet to- Ward a first of said ports in accordance with the rate and direction of flow through said ports and outlet, the improvement wherein said valve member is elongated, said valve member having a rounded end portion adapted to seat upon a surface defining a circular cross-sectioned converging passageway, for closing said outlet, said elongated valve member in the closed position extending from said rounded end portion past said second port in the direction of said first port, said valve member defining oppositely directed piston surfaces, the first piston surface directed toward said first port, opposite from said outlet, and exposed to the pressure influence of said first port at all positions, and the second, oppositely directed piston surface exposed to the pressure influence of said second port at all positions, means including said movable valve being joined to said mid-portion and being enlarged to a substantially greater cross-sectional area, the free end surface of said enlarged portion defining said first piston surface, the free surface of said enlarged portion directed oppositely from said first piston surface defining, at least in part, said second piston surface, said enlarged portion being rounded, at least on its lateral sides, and a circular cross-sectioned seating surface positioned adjacent said first port in the path of said elongated member to be engaged by said rounded surface, to restrain said valve member without allowing it to bind when said pressure at said first port is reduced.

12. A spray nozzle useful with fluid that contains debris particles, the nozzle having a passage, an outlet for said passage, a supply port to introduce fluid to said passage, a second port communicating with said pas-sage between said supply port and said outlet, a strainer means located between said ports, and means to cause the pressure preceding said strainer means to become less than the pressure at said second port to produce a back-flow of fluid that cleans said strainer means characterized by the fact that said strainer means comprises a restriction in said passage which prevents the flow of debris particles to said outlet, said restriction defined on one side by a pressure responsive movable member, "said member adapted to move when the pressure at said supply port becomes less than the pressure at said second port, said movement adapted to aid removal of debris.

13. The spray nozzle of claim 12 characterized by the fact that at least upon initial movement said pressure responsive movable member is adapted to increase the size of said restriction in said passage to help the removal of debris by back-flow of fluid.

14. A spray nozzle useful with fluid that contains debris particles, the nozzle having a passage, an outlet for said passage, a supply port to introduce fluid to said passage, a second port communicating with said passage between said supply port and said outlet, a strainer means located between said ports, and means to cause the pressure preceding said strainer means to become less than the pressure at said second port to produce a back-flow of fluid that cleans said strainer means characterized by the fact that there are provided an auxiliary outlet and a pressure-responsive valve means, known per se, the valve means adapted to open said auxiliary outlet in response to the change in pressure that causes cleaning of said strainer means.

15. A spray nozzle useful with fluid that contains debris said supply port and said outlet, a strainer means located between said ports, and means to cause the pressure pre ceding said strainer means to become less than the pressure at said second port to produce a back-flow of fluid that cleans said strainer means in combination with at least one additional nozzle of like configuration and a supporting pipe, an elongated divider wall member extending along the length of said pipe and supported by the inner walls of said pipe, said divider Wall member dividing said pipe into two elongated compartments, the supply ports of each of said nozzles communicating with a first of said compartments, thesecond ports communicating with the other of said compartments, said first compartment adapted to supply fluid to all of said first ports and second ports adapted to enable flow of strained fluid from a first to a second nozzle upon clogging of the strainer of said second nozzle, said first compartment also adapted, upon purging operation, to receive debris from all of said nozzles and conduct it away.

16. A shower system having a multiplicity of strainer nozzles each nozzle having a passage, an outlet for said passage, a supply port to introduce fluid to said passage, a second port communicating with said passage between said supply port and said outlet, a strainer means located between said ports, and means to cause the pressure preceding said strainer means to become less than the pressure at said second port to produce a back-flow of fluid that cleans said strainer means characterized by the fact that the second ports of all of said nozzles are connected to a common passage, whereby in the event that the strainer means of a nozzle becomes filled with debris, the outlet of said nozzle can receive strained fluid through an auxiliary supply path defined by the second port of said nozzle, said common passage and the second port and strainer means of other nozzles.

References Cited by the Examiner UNITED STATES PATENTS EVERETT W. KIRBY, Primary Examiner. 

16. A SHOWER SYSTEM HAVING A MULTIPLICITY OF STRAINER NOZZLES EACH NOZZLE HAVING A PASSAGE, AN OUTLET FOR SAID PASSAGE, A SUPPLY PORT TO INTRODUCE FLUID TO SAID PASSAGE, A SECOND PORT COMMUNICATING WITH SAID PASSAGE BETWEEN SAID SUPPLY PORT AND SAID OUTLET, A STRAINER MEANS LOCATED BETWEEN SAID PORTS, AND MEANS TO CAUSE THE PRESSURE PRECEDING SAID STRAINER MEANS TO BECOME LESS THAN THE PRESSURE AT SAID SECOND PORT TO PRODUCE A BACK-FLOW OF FLUID THAT CLEANS SAID STRAINER MEANS CHARACTERIZED BY THE FACT THAT THE SECOND PORTS OF ALL OF SAID NOZZLES ARE CONNECTED TO A COMMON PASSAGE WHEREBY IN THE EVENT THAT THE STRAINER MEANS OF A NOZZLE BECOMES FILLED WITH DEBRIS, THE OUTLET OF SAID NOZZLE CAN RECEIVE STRAINED FLUID THROUGH AN AUXILIARY SUPPLY PATH DEFINE BY THE SECOND PORT OF SAID NOZZLE, SAID COMMON PASSAGE AND THE SECOND PORT AND STRAINER MEANS OF OTHER NOZZLES. 